1. Field of the Invention
The present invention concerns a sorting table featuring grading rolls with modifiable and adjustable gaps. This sorting table may be fitted to perform the elimination of foreign objects being mixed in with the products of harvested small fruit; it may also be adapted to enable calibration of various agricultural, food products or other items, according to their size or caliber. It applies also to harvesting machines, in particular to grape picking machines featuring one or several sorting tables with grading rolls, as well as, in a more general manner, to installations, especially to stationary sorting installations that may for instance be built in cellars, in the grape crop receiving area or any other crop in the cellar.
The invention also concerns a process of modifying and adjusting the gap between the grading rolls of a sorting table.
According to a particularly interesting application, the sorting table with grading rolls according to the invention has the purpose to ensure the elimination of foreign objects (stalks, leaves, leaf or vine shoots, splinters of pickets or stakes, mineral debris, insects, small animals, etc.) that are mixed in with the grapes after stripping the grapes from the stalks, or with other products of the harvest of small fruit such as gooseberries, black currant, blackberries, raspberries, lingonberries, cranberries, olives, etc.
According to another possible application, the sorting table according to the invention may be laid out so as to permit calibration of various agricultural, food or other products such as potatoes, onions, garlic bulbs, French fries, apples, pears, shrimp and other crustaceans, etc.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
A sorting table with grading rolls more specifically intended to extract undesirable objects from a flow of fruit clusters spread out on said sorting table is for instance described in document EP-2.030.498. According to this document, this sorting table features a sorting system consisting of a succession of adjacent rotating rolls of a generally cylindrical shape in a parallel arrangement so as to form a sorting plane, and of motors for driving said rolls in the same direction, thus ensuring the transportation of the grape harvest crop dropped on the upstream part of this sorting plane, in a direction that is perpendicular to the axis of said cylindrical rotating rolls and over the entire length of said sorting plane, said cylindrical rotating rolls turning in place and being positioned so as to provide a number of openings between two adjacent rolls, in order to permit only the small fruit to be sorted to pass through and drop down, while any foreign objects larger than the fruit remain on the surface of the moving sorting plane and will be removed at the downstream end.
The sorting table with rotating rolls described in the aforementioned document yields excellent results in the application for which it is more specifically intended. However, it is not suitable for sorting grape berries or other clusters with considerable variations of size.
As a matter of fact, one of the major constraints faced by users of sorting tables with rolls featuring pass-through openings with a fixed cross section is the result of significant variance in size of the harvested products (for example the significant variance of the size of grape clusters depending on the grape varieties, etc.).
A primary solution allowing to vary the cross section of the pass-through openings made between the rolls consists of modifying their profile. However, this makes it necessary to have available several sets of rolls with different profiles and to remove and install all the rolls, depending on the size of the items to be sorted, which can be time consuming, complex and costly.
Mechanical solutions have been proposed (FR-2.511.575, FR-2.9938.157, U.S. Pat. No. 5,2927,427, GB-2.277.046, EP-0.951.950, DE-1.965.243, U.S. Pat. No. 7,117,996) to modify the gap between the calibration rolls and/or the cross section of the pass-through openings for the fruit, provided between the rolls.
However, these solutions utilize complex mechanical systems of design and operation which do not extend, in certain cases, beyond the realm of purely theoretical propositions.
Furthermore these systems:                do not permit overriding their sorting or calibration function while maintaining their function of conveying the harvested product; and        do not offer any security against the risk of damage which could result from the presence in the crop of a hard object getting stuck between two adjacent rolls.        